public class changliangyubianliang {
        // 常量定义（使用final关键字）
        public static final double PI = 3.141592653589793;
        private static final String APP_NAME = "变量演示程序";

        public static void main(String[] args) {
            // 变量声明与初始化
            int age = 20;
            double salary = 5000.50;
            char gender = 'W';
            boolean isEmployed = true;
            String name = "马周淼";

            // 变量重新赋值
            age = 20;
            salary = 1000000;

            // 使用常量
            double circleArea = PI * 5 * 5;

            // 输出结果
            System.out.println("应用名称: " + APP_NAME);
            System.out.println("姓名: " + name);
            System.out.println("年龄: " + age);
            System.out.println("性别: " + gender);
            System.out.println("月薪: " + salary);
            System.out.println("就业状态: " + isEmployed);
            System.out.println("半径为5的圆面积: " + circleArea);
            // 类型转换示例
            int intSalary = (int)salary;
            System.out.println("整型月薪: " + intSalary);
        }

}
